Various cooking ovens have a permanent front access opening for frequent input and retrieval of food items from the access opening. The open view of cooking in a restaurant also gains the customers' appreciation of the genuine food preparation process. However, the heat and exhaust exiting from the access opening are undesirable, which elevate surrounding environment temperature and release smoke, dust and smell into the surrounding area. Consequently, it is required in the United States that a hood has to be installed in front of the access opening of an oven to vent out the exhaust exiting from the access opening.
Therefore, it is desirable to have an oven which has a structure or a mechanism to inhibit the heat and exhaust from exiting from the access opening.